If you can't get your hands on a pair of solar eclipse glasses, experts say there are still ways to enjoy the event safely.

There are also unsafe alternatives, including wearing your normal sunglasses — or even stacking two or three.

"There's no amount of sunglasses that people can put on that will make up for the filtering that the ISO standard filters and the eclipse glasses provide," said Dr. Jason P. Brinton, an ophthalmologist and medical director at Brinton Vision in St. Louis.

You also shouldn't look at the eclipse through a camera lens, phone, binoculars or telescope, according to NASA, even while wearing eclipse glasses. The solar rays can burn through the lens and cause serious eye injury.

So what can you use? Here's what doctors suggest:

How to make your own eclipse-safe glasses at home

If you don't have the traditional solar eclipse glasses, Brinton said you can also look through No. 14 welder's glasses (for people who may have access) or aluminized mylar plastic sheets.

Just like with traditional solar eclipse glasses, Brinton said it's important to make sure the material you're viewing through is fully intact.

"Make sure that there are no scratches or damage," he said. 

How make a pinhole projector for safe eclipse viewing

No glasses? Indirect viewing is another way to enjoy the eclipse without damaging your eyes. 

Brinton said there are several ways to indirectly view the event, including a homemade pinhole projector. Here's how to make one:

• Put a small pinhole into a piece of paper
• Face away from the sun, holding the paper out so the sunlight hits it
• Watch the pinhole projection of the sun on the ground (or on a second piece of paper you hold underneath), seeing it go from a complete circle gradually disappearing 

"If you're in the path of totality, of course it completely disappears." Brinton said. "That's an indirect way of viewing it that is appropriate."

How to make an eclipse viewer from a cereal box

If you want to make your indirect viewing tool a bit more elaborate, you can make an eclipse viewer with a few more materials around the house. Here's how:

• Find a small box (popular options are cereal and shoe boxes)
• Cut two openings at the bottom of the box
• Using tape, cover one of the openings with a piece of paper or aluminum foil punctured with a small pinhole
• Face away from the sun, allowing the light to hit the pinhole
• Looking through the remaining opening to the inside of the box, watch as the sun projection goes from a complete circle to an eclipse

Need a visual? CBS Pittsburgh meteoroligist Ray Petelin demonstrated an easy step-by-step on how to make a cereal box pinhole viewer, which you can watch below.

Doctors share how to make sure your eclipse viewers are safe

"Theoretically, since you are not looking directly to the sun during the eclipse or partial eclipse, (eclipse viewers) should be safe," said Dr. Yehia Hashad, an ophthalmologist, retinal specialist and the chief medical officer at eye health company Bausch + Lomb. "However, having said that, it's implementation that sometimes makes us worry."

• Are your eclipse glasses safe? Here's how to know if they'll really protect your eyes during the total solar eclipse.
  

Why? Sometimes people have a small peek at the sun in order to adjust the box or pinhole in the right direction, he said. This can be especially common with children, who may not understand the consequences of looking at the eclipse.

"This is what makes us sometimes conservative about this method," said Hashad. "We always worry, unless you are supervising the implementation of this, especially with children since they are very vulnerable to these types of situations."

Why do you need a special viewer for the total solar eclipse?

Eye protection during the eclipse is important to prevent eye damage.

"If someone briefly looks at the eclipse if it's extremely brief, in some cases there won't be damaged but damage can happen even within a fraction of a second in some cases," Brinton said. "As an ophthalmologist, I have seen patients who have so-called eclipse or solar retinopathy."

Signs and symptoms of eye damage following an eclipse viewing include headaches, blurred vision, dark spots, changes to how you see color, lines and shapes.

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• Eclipse